Collet connectors are commonly used to interconnect subsea equipment, for example a spool body and a wellhead hub, or a pipeline end and a manifold.
The state of the art includes U.S. Pat. No. 4,708,376, which discloses a collet-type connector having an upper body with a plurality of collet segments, a cam ring movable relative to the upper body member in order to move the collet segments into a detachable connection of the connector to a subsea wellhead. The cam ring and collet segments have sets of camming surfaces whereby a first set cooperate to pivot the collet segments initially towards the wellhead and whereby a second set serves to urge the collet segments further to clamp the connector to the subsea wellhead. When the second set of camming surfaces are in operation, the first set no longer function to rotate the collet segments, thus reducing the power requirement for urging the collet segments into clamping engagement to only one set at a time, even though both sets together serve to aid in holding the collet segments in clamping engagement with the wellhead after final engagement. When executing the connection, one set of camming surfaces initially serves to hold the collet segments in a conical orientation to facilitate positioning the connector over the wellhead and, secondly, together with the complementary ledges to form a load path between the collet segments and the upper body member so that any load on the connector as it is being placed in the wellhead will be transferred to the upper body member. The means for actuating the cam ring are hydraulic cylinders.
The state of the art also includes WO 2010099269, which discloses a subsea connector having an adapter ring that is capable of connecting the spool body to the connector. The connector assembly may be lowered onto a wellhead member and locked into place by a movable piston and split lock ring. While the connector assembly is in the unlocked state, the adapter ring may be rotated, moving the connector up or down with respect to the spool body, which lands on the wellhead member. The connector assembly is not locked to the wellhead member until the connector piston is moved to a locked position within an internal cavity of the connector. The movement of the connector may be used to vary the alignment of the connector locking means with respect to the locking profile of the wellhead member. This change in position may be used to modify the preload force applied to the connector when locked onto the wellhead member.
Thus, in the prior art, the first set of camming surfaces serves primarily to pivot the collet segments towards the wellhead hub (the second set performing the clamping operation), and the connector assembly is not locked to the hub until a connector piston subsequently is moved to a locked position.
The connectors of the prior art are limited in their ability to enter the hub at a large deflection angles and are limited with respect to the level of pre-tension that may be applied to the connector. Also, the collet fingers of the known connectors are prone to excessive wear and tear when aligning the connector with the hub, because of the manner in which the fingers are pre-tensioned.
The present applicant has devised and embodied this invention in order to overcome these shortcomings and to obtain further advantages.